There have been conventionally known tunnel boring machines having a cutter head. An example of such tunnel boring machines is disclosed in Japanese Patent No. 2738897.
The tunnel boring machine disclosed in Japanese Patent No. 2738897 includes a cutter head, an intermediate beam that supports the cutter head, and a cutter driving unit for rotationally drive the cutter head and the intermediate beam. The tunnel boring machine advances forward by a thrust force of a thrust jack, while rotating the cutter head by the cutter driving unit.
Prior to boring using a tunnel boring machine, a boring investigation can be performed to roughly grasp the geology of the boring route. However, it is difficult to accurately grasp the presence of unexpected buried objects and the change of strata in advance. Therefore, boring is advanced while monitoring the cutter torque (the rotational torque of the cutter driving unit), a jack thrust (a thrust force of the thrust jack), boring speed and the like.
In boring, the tunnel boring machine may advance while straddling different strata or encounter buried objects or stones. In such cases, the cutter head may be subjected to an eccentric load (deviation of forces acting on the cutter head). The eccentric load may cause damage to the cutter head and the cutter driving unit and abnormal wear of cutter bits (boring edges).